It's not just of question of libraries. By itself most of the codebase in odoo/openerp isn't compatible with Python3. And by that I mean that openerp was written using syntaxes that aren't compatible with python3.

One easy example is the usage of the boolean operator '<>' instead of '!='. On other example is the syntax used for exceptions.

So the real big problem isn't exactly in third party libraries but the openerp library itself and the addons.